Investigating the Possibility of Increasing the Physiological Function of (Lippia citriodora L.) Using Biological Stimuli under Salinity Stress Conditions

Environmental stresses are one of the most important factors in reducing the function of medicinal plants. The use of plant growth regulators such as PGPR can be a way to reduce the effects of salinity stress. Environmental factors, cause changes in the growth of medicinal plants and, on the other hand, alter the amount and quality of their active substances, such as alkaloids, glycosides, steroids, volatile oils (essential oils). The experiment was conducted factorial based on a randomized complete block design with 12 treatments in four replications at greenhouse of University of Kashan. The first factor was salinity stress at 3 levels including 25, 50 and 100 (MM) Mili molar and salinity treatments were performed after complete sowing of cultivated plants. The second factor was bacterial growth stimulus in four levels including control (0), 10-10, 10-8 and 10-6 molar and the addition to the potted soil as a solution before applying salinity stress. It was found that the use of plant growth regulator PGPR is essential for maintaining the economic performance of plants under stress. The results showed that increased levels of salinity had a significant effect on reducing the growth parameters including dry weight, root length, plant height and essential oil yield. According to the results, the percentage of essential oil with increased levels of salinity significantly at 1% level, so that the percentage of essential oil from 0.45 in 25 (MM) treatment was increased to 0.96 in 100(MM) and the use of 10-8 M PGPR.